Aligning and fixing the fiber and laser device is an important work in butterfly laser module packaging. Assembling these two component by laser welding is to achieve reliable and stable weld joint. However, during the welding process, rapid solidification of the welded region and the associated material shrinkage causes the fiber position moved. The relative movement between fiber and laser is called post-weld-shift(PWS). A few micrometers PWS makes coupled power lost. Therefore, minimizing the PWS between fiber and laser is a key research topic in butterfly laser module packaging. We can correct the PWS minimal by fiber shift inspect. But it has a difficult of space limit in butterfly laser module packaging. In this study, a video camera with image acquisition system was used to measure the PWS. We also used a mirror image to solve the problem of space limited. The PWS inspection result has matched our simulation. This method can successfully inspect the PWS in butterfly laser module.

Semiconductor ring laser diodes (SLD) have been receiving attention for their potential use as source in photonic integrated circuits. Advantages of a ring laser include ease of integration because of no need for cleaved facets and they can be made very compact by folding their cavity . Ring laser have a unique feature, clockwise and counter- clockwise, in their lasing modes. If unidirectional traveling-wave oscillation can be achieved, spatial hole burning effects seen in Fabry-Perot and distributed feedback lasers can be avoided. In this work, the unidirectional oscillation is accomplished by controlling the taper shape structure. The whole laser cavity is formed using four reflection mirrors (TIR) and an output coupler passive waveguide. According to the Beam propagation Method (BPM) simulation, we find that the clockwise and counterclockwise oscillations have different behavior under various taper shape , indicating bidirectional oscillation can be eliminated. Moreover, bending loss¡Bmode transformation and optical gain are all included in calculation model. The waveguide is fabricated in the following steps: (1) ion implantation to get electrical isolation (2) selectively wet etching to form waveguide ridge (3) evaporation n- and p- electrode (4)spatter with Si3N4(5) planarization (6) evaporation microwave transmission line.

This piece makes the claim that rhetoric is first philosophy--before philosophy, epistemology, ontology, or any other field--or that rhetoric is, at the least, on equal footing as these fields because: empathy--and thusly the impulse for communication--is physiologically hardwired into humans; special distinctions between human and animal are largely artificial constructions, as is evidenced by neurosciences; "hard" science, in the form of neurosciences, is providing entrance points & opportunities for rhetoric to raise its status within the academy; and said neurosciences, in addition to empathy studies, have shown strong evidence supporting linguistic and evolutionary links between humans and other species, thereby supporting a "preoriginary rhetoricity," in Diane Davis's terms. Davis's Inessential Solidarity... serves as a stepping stone for this piece in the sense that the ethical relation as derived from the work of Levinas, originary rhetoricity, and rhetorics of the saying or of the address require the utmost attention for rhetorical scholars right now. I show how neuroscience research might help Davis's project--in which she is far from alone--move forward by providing connections between rhetoric and current neuroscience work.

We have demonstrated a flexible optical waveguide film with integrated VCSEL and PIN photodiode arrays for the fully embedded board level optical interconnection system. One of the most critical issues in the fully embedded board level optical interconnection system is the signal beam coupling between the guided-wave structure and the aperture of VCSEL (or PIN photodiode). The coupling efficiencies of spherical mirrors are calculated as a function of mirror radius. The optimum mirror radius ranges which are compatible with the fully embedded board level optical interconnection system are theoretically verified. The thermal characteristics of a thin film VCSEL are studied both theoretically and experimentally. The thermal resistances of VCSEL with variable thickness, ranging from 10 [mu]m to 200 [mu]m, have been determined by measuring the output wavelength shift as a function of the dissipated power. The thermal simulation results agree reasonably well with experimentally measured data. From the thermal management point of view, a thinned VCSEL has an exclusive advantage due to the reduction of the thermal resistance. The thermal resistance of 10 [mu]m thick VCSEL is 40 % lower than that of 200 [mu]m thick VCSEL. The theoretical analysis of thermal via effects is performed to determine optimized thickness ranges of thin film VCSEL for the fully embedded structure. Thermal resistance of the fully embedded thin film VCSEL with closed and open thermal via structures are also evaluated with the suitable VCSEL thickness reported. The high-performance computing system is demonstrated using a 16-channel optical backplane using thin film volume holographic gratings. The optical backplane contains TO-46-Can-packaged VCSELs and photodiodes as an optical transmitter and receiver, respectively. Optical packaging plates are fabricated for 4 X 8 array packaging for 16-VCSELs and 16-Photodiodes. Packaging issues including crosstalk and alignment tolerance are studied to design a low cost optical packaging scheme. Thin film volume hologram grating is fabricated on glass substrate to redirect light beams. An individual single channel performs at a 100 MHz data transfer rate. The high-performance computing system using 16-channel optical backplane is demonstrated at a 1.6 Gbps data transmission. / text

We describe combinatorial techniques for studying log Calabi-Yau surfaces. These can be viewed as generalizing the techniques for studying toric varieties in terms of their character and cocharacter lattices. These lattices are replaced by certain integral linear manifolds described in [GHK11], and monomials on toric varieties are replaced with the canonical theta functions defined in [GHK11] using ideas from mirror symmetry. We classify deformation classes of log Calabi-Yau surfaces in terms of the geometry of these integral linear manifolds. We then describe the tropicalizations of theta functions and use them to generalize the dual pairing between the character and cocharacter lattices. We use this to describe generalizations of dual cones, Newton and polar polytopes, Minkowski sums, and finite Fourier series expansions. We hope that these techniques will generalize to higher rank cluster varieties. / text

Three models for the generation and propagation of hydrodynamic noise near the ocean surface are presented, and are compared for their ability to predict hull noise generated by CFAV Quest. The simulated fluctuating pressure field on the hull is also validated against experimental results. The near field flow is first solved using the NWT CFD package, and the hydrodynamic noise is calculated using the Lighthill-Curle acoustic analogy. The far field sound is obtained using three methods: a method of images solution to the Lighthill-Curle equations, a simple source model of the transmission loss, or a normal mode model of the transmission loss. Both the simple source and method of images models improve the SPL predictions of the Lighthil-Curle equations. Best performance is obtained from the method of images, improving predictions by approximately 40 dB. The normal mode model is shown to give poor results, due to assumed sea-floor boundary conditions.

No description available.

In this work a low voltage and highly linear current-mode current to delay (CTD) converter is presented. The proposed current to delay converter has the improved linearity of about 23.5% when compared with a conventional–delay inverter over the input dynamic current range of 50µA. When used as front-end block in current-mode delay-mode analog to digital converter an 11-bit resolution is obtained. The design is implemented in TSMC 90 nm CMOS technology. Monte Carlo analysis and process corner analysis is performed on the proposed circuit to analyze the amount of mismatch that will degrade the performance of the circuit in a system level. A Process, Voltage, and Temperature (PVT) variation insensitive circuit is used to bias the designed CTD converter to obtain 57% reduction of variation when compared with the simple current mode biasing technique.

Segmented mirrors are to be used in the next generation of the ground-based optical telescopes to increase the size of the primary mirrors. A larger primary mirror enables the collection of more light, which results in higher image resolutions. The main reason behind the choice of segmented mirrors over monolithic mirrors is to reduce manufacturing, transportation, and maintenance costs of the overall system. However, segmented mirrors bring new challenges to the telescope design and control problem. The large number of inputs and outputs make the computations for centralized control schemes intractable. Centralized controllers also result in systems that are vulnerable to a complete system failure due to a malfunction of the controller. Distributed control is a viable alternative that requires the use of a network of simple individual segment controllers that can address two levels of coupling among segments and achieve the same performance objectives. Since segments share a common support structure, there exists a coupling among segments at the dynamics level. Any control action in one segment may excite the natural modes of the support structure and disturb other segments through this common support. In addition, the objective of maintaining a smooth mirror surface requires minimization of the relative displacements among neighbouring segment edges. This creates another level of coupling generally referred to as the objective coupling. This dissertation investigates the distributed H∞ control of the segmented next generation telescope primary mirrors in the presence of wind disturbances. Three distributed H∞ control techniques are proposed and tested on three segmented primary mirror models: the dynamically uncoupled model, the dynamically coupled model and the finite element model of Thirty Meter Telescope (TMT) project. It is shown that the distributed H∞ controllers are able to satisfy the stringent imaging performance requirements. / Graduate / 0548

<p>Plastic Recognition traces a critical genealogy of the human face in cinema and its afterlives. By rethinking the history of film theory through its various investments in the face, it seeks to intervene not only in the discipline of film studies but more broadly within contemporary political and scientific discourse. This dissertation contends that the face is a privileged site for thinking through the question of recognition, a concept that cuts across a range of aesthetic, political, philosophical, and scientific thought. Plastic Recognition examines this intimate link between the face and recognition through a return to "classical" film theory, and specifically to the first generation of European and Soviet film theorists' preoccupation with the face in silent cinema. In the process, it recasts the canonical debate over cinematic specificity between Béla Balázs and Sergei Eisenstein as an antagonism between two opposing conceptions of the face in film: transparent universalism versus plastic typicality. Of these two conceptions, this project contends that the "Balázsian" idea of a transparently expressive face assumes cultural dominance in the latter half of the 20th century by virtue of its essential commensurability with the political and social ideal of mutual recognition that has come to prevail in the United States and Western Europe in the context of neoliberalism. Alongside and against this dominant tendency, the "Eisensteinian" insistence upon the plasticity of aesthetic form provides a radical alternative to the idealist metaphysics of immediacy underlying both the "Balázsian" notion of the cinematic face and the ideal of mutual recognition it exemplifies. That insistence forces into view the ways that recognition itself is always contingent upon aesthetic and technological practices, even (or especially) when it is brokered by that seemingly most immediate of images--the human face. By adopting this approach as its basic critical orientation, this dissertation attempts to restage the problem of recognition as fundamentally about the historicity of plastic form. The project concludes by turning to a scientific scene of recognition in which the "Balázsian" conception of the face makes an uncanny reappearance. The final chapter examines several studies in contemporary neuroscience that use representations of the human face as experimental stimuli in an effort to establish a neurophysiological basis for the mutual recognition of empathy.</p> / Dissertation